In recent years, the development of the so-called silicon photonics technology to realize an optical communication module by forming optical waveguides (optical signal transmission paths) made of silicon (Si) in a part of a silicon substrate and integrating optical circuits and electronic devices constituted of the optical waveguides has been actively pursued.
The semiconductor device in which optical waveguides made of silicon are formed in a part of a silicon substrate consumes extremely low power, and has favorable advantages of being able to realize a small-sized optical communication module by forming silicon integrated circuits and optical waveguides in the same silicon substrate.
Andy Eu-Jin Lim et al., “Review of Silicon Photonics Foundry Efforts” IEEE Journal of selected Topics in Quantum Electronics Vol. 20. No. 4 July/August 2014 (Non-Patent Document 1) discloses an optical semiconductor device in which a heater made of a titanium nitride (TiN) film is formed on an insulating film over a silicon optical waveguide formed in a part of an SOI substrate.